Geoscience Reference
In-Depth Information
ranged from 1-4 km in visible and in infra-red. In December 1970 the successor of
ESSA became known as NOAA-1. NOAA refers to the National Oceanic and
Atmospheric Administration. The NOAA satellites were used by the US Department
of Commerce to produce images for operational and commercial purposes. This first
series of NOAA satellites were equipped with a very high resolution radiometer
(VHRR) and a vertical temperature sounder. In 1975, the second generation of
Russian METEOR satellites was also equipped with an imaging radiometer. The
first high-resolution observation satellites were also sent into orbit during the 1970s.
These satellites included LANDSAT MSS in 1972, and then SPOT in 1984.
An important turning point occurred in 1978 with the arrival of a new generation
of NOAA sensors. The advanced very high resolution radiometer (AVHRR), which
was on board the TIROS-N that was launched in 1978, observed the Earth's surface
in four different spectral bands: 0.55-0.9 μm, 0.73-1.1 μm, 3.5-3.9 μm, and 10.5-
11.5 μm. From the NOAA-6, and for any subsequent NOAA satellite, the passing
band of channel 1 was reduced in size so that it would be easier to see and
distinguish between different cloud cover (0.55-0.7 μm then 0.58-0.68 μm). It has
been possible to calculate vegetation indexes since 1980. These indexes combine
information gathered in channels 1 and 2, which is close to the infrared region of the
electromagnetic spectrum. From the NOAA-7 and for any subsequent satellite a
fifth channel was added to the sensors (with a spectral band 11.5-12.5 μm) with the
aim of improving estimations of temperatures relating to the surface of the sea
[DSO 96].
In 1998, the AVHRR-3, which was installed on board the NOAA-15, had a sixth
channel added to it (with a spectral band of 1.58 - 1.64 μm) to carry out research on
ice and snow. In 1978 a series of experimental platforms, such as SEASAT and
NIMBUS, were launched. The 1980s was the decade in which long-term operational
programs were created, some of which are still functioning today. Great efforts were
also made so that it could be possible to integrate satellite data into different
weather-forecasting models. The first global model, which stored data relating to
wind (produced by geostationary platforms on a daily basis), was created at the
European Centre for Medium-Range Weather Forecasts (ECMWF) in Reading in
August 1979 [PAI 02]. The focus, however, seemed to be on the development of
different models, and the actual meteorological spatial technical was forced into the
background. Scientists were focused on a new perspective based on global change;
as a result, the benefits of remote sensing were not fully appreciated.
The 1990s were also marked by a series of problems and the arrival of a new
generation of sensors. The different satellite programs experienced a wide range of
problems, and these included: the explosion of the space shuttle Challenger, during
take-off in 1993; difficulties associated with the development and upgrading of the
GOES-next series (a three-way stabilization system); the failure of the LANDSAT 6
mission; and the loss of the NOAA-13 satellite in 1993 after being in orbit for only
13 days, etc. At the same time, however, new observation systems were being
created and these included: radar images and altimetric radars (TOPEX Poseidon,
ERS, etc), as well as atmospheric sounding instruments that produced better results
